How to Repair a Crack in Concrete Foundations Using Hydraulic Cement

Concrete foundations often become cracked because of settlement and movement in the dirt below the foundation. Sometimes these cracks may be minor and will require no immediate attention, but more often, these cracks need to be repaired using hydraulic cement. The average do-it-yourself homeowner can repair a foundation crack using hydraulic cement in six to eight hours, depending on the size and scope of the project.

Things You'll Need

Screwdriver

Wire brush

Water hose/spray nozzle

Air blower tip

Hydraulic cement

5-gallon bucket

Sand

Paddle mixer

Pointing trowel

Water misting bottle

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Clean out the foundation crack. Debris from the cracks will often remain in the crack and prevent the insertion of hydraulic cement. Use a flat-head screwdriver to gouge out the loose concrete flakes. Be careful not to break away more material. Use the wire brush to brush the crack and remove fine particles.

Wash the crack using a water hose. Place a spray nozzle on the hose and spray pressure on the crack. Use an air blower if you are inside your basement and you cannot apply high pressure with a water hose.

Mix hydraulic cement in a 5-gallon bucket. Use a paddle mixer inserted into a drill to mix the cement. Mix the cement at a ratio of 2-to-1, meaning two parts cement and one part sand. Add two cans of cement powder and one can of sand using an old coffee can. Add water as you mix with the paddle mixer. Make the consistency similar to clay. Add in small amounts any water, cement powder or sand you may need to get the mixture right.

Pack the cement into the foundation crack using a small 6.5-inch pointing mason's trowel. Gather a small amount of cement on the back of the trowel and press into the crack. Keep packing until the crack is completely full. The cement will expand after an hour or so. Cut the excess cement off the foundation with the edge of the trowel before the cement gets too hard. Use a spray bottle and water to keep the cement moist, spraying the patch every hour for six hours. It will keep the cement from cracking.